The ongoing goals of our research program are: (a) to establish the early emergence of behavioral risk factors for cardiovascular (CV) disease in children and adolescents; and (b)to specify their antecedents and consequences. Our current project, which tested the influence of gender and ethnicity, found that behavioral and biological risk factors cluster together in children, resulting in a substantial overall burden among some children that is not apparent by studying the development of individual risk factors alone. Building on our current findings, we propose that the effects of socioeconomic status (SES) and ethnicity are intertwined, and are partly due to greater exposure to environmental stress, especially social conflict. Repeated exposure to social conflict encourages the development of a propensity to be vigilant for possible threat, to view ambiguous situations as potentially harmful, to mistrust others, and to exhibit elevated CV reactivity during potential threat. We suggest that these propensities become more automatic and repeatable with adolescent development, leading to stable dispositions. Dispositions, in turn, may influence markers of CV risk, namely total blood pressure burden, aortic stiffness, and left ventricular mass. These were chosen to taken advantage of recent technological improvements and advances in understanding the development of CV risk. To test these proposed relationships, we will recruit 100 adolescent African American and 100 Whites, with approximately equivalent numbers of upper and lower SES based on parental education and occupation within each ethnic group. Each participant will complete a psychophysiological laboratory protocol, questionnaires, carotid scan and echocardiogram in a single morning session, and two school days of ambulatory blood pressure monitoring accompanied by diary ratings of stressful circumstances at the time of each measure. This design allows us to test the influence of SBS and social stress on the development of behavioral risk factors and to test the extent to which behavioral risk factors mediate associations between sociodemographic factors, stress, and CV markers in adolescents.